Timeline misunderstanding

Hello,
When I click on an area, let's say in the mediterannean, then I click on "Forecast for this location", I get presented with a series of information with a red and white timeline at the top. When I hover over the timeline, a time is displayed in a red "message box" but as soon as I click, a time appears in a white "message box". This time is constantly 2 hours earlier.
Can someone explain to me why that is?
What time I should refer to?
How to perhaps change it?

Great help would be appreciated, I would not mind giving further explanation if needed!